Organic Matter Decomposition: Interactions of Temperature, Moisture and Substrate Type

The decomposition of organic matter is a major biogeochemical process because of its effect on ecosystem productivity and its implications on climate change. Temperature and moisture are two variables that have a tremendous influence on microbial decomposition. Decomposition is also influenced by substrate type, in which higher quality substrates often have greater decomposition than lower quality substrates. Pine and hardwood litters, popsicle sticks, aspen and pine wood stakes were subjected to 4 temperature treatments (10oC, 20oC, 30oC, and 40oC) and 4 moisture content treatments (wet 23-28%, moist 15-20%, dry 3-7%, & fluxing between 3-7% and 23-28% saturation ) over the course of 30 months, in order to determine the influence of temperature, moisture, and substrate type on decomposition. As a subset of the experiment soil respiration was recorded from one pvc collar with leaf litter and one without litter and was subjected to the same treatments. There were different responses with different substrates, but overall microbial decomposition was greatest at the highest temperatures. For the wood substrates the “moist” and “dry” moisture contents generally produced the highest mass losses. The pvc collar’s highest soil respiration rates were with the “wet” moisture treatment. Temperature and moisture are both significant in decomposition, but the moisture relationship interaction with decomposition is much harder to understand.